Eur. Phys. J. Plus (2022) 137: 312
https://doi.org/10.1140/epjp/s13360-022-02519-8

Regular Article

Ionic current magnetic fields in 3D finite-length nanopores and nanoslits

¹ School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran
² Department of Mechanical Engineering, HCT, DBM, Dubai, UAE
³ Department of Mechanical Engineering, Lakehead University, Thunder Bay, ON, Canada

^d chini@ut.ac.ir

Received: 15 November 2021
Accepted: 23 February 2022
Published online: 7 March 2022

Abstract

Deoxyribonucleic acid (DNA) encodes all genetic information, and in genetic disorders, DNA sequencing is used as an effective diagnosis. Nanopore/slit is one of the recent and successful tools for DNA sequencing. Passage of DNA along the pores creates non-uniform ionic currents which creates non-uniform electric and magnetic fields, accordingly. Sensing the electric field is usually used for sequencing application. We suggest to use the magnetic field induced by pressure-driven ionic currents as a secondary signal. We systematically compared the induced magnetic field of nanopores and nanoslits with equal cross-sectional area. The 3D magnetic field is numerically obtained by solving the Poisson-Nernst-Planck, Ampere, and Navier–Stokes equations. As expected, the maximum value of the maximum magnetic flux occurs near the wall and inside the channel, and increasing the pressure gradient along the pore/slit increases the flowrate and magnetic field, consequently. At a given pressure difference across the pore/slit, nanopores are better than nanoslits in sensing the magnetic flux. For example, by applying 2 MPa across the pore/slit, the maximum magnetic flux density for nanopore, nanoslit $AR=1$ and nanoslit $AR=5$ are 1.10 pT, 1.08 pT and 0.45 pT, accordingly. Also, at a given flowrate across the pore/slit, nanoslits are the better choice. It should be noted the external magnetic fields as small as pico-Tesla are detectable and measurable in voltage/pressure driven electrokinetic flow slits.